1. Field of the Invention
The invention relates to spray assemblies and soil load sensing devices for automatic dishwashers.
2. Description of the Related Art
Conventional household automatic dishwashers frequently have rotating spray arms for spraying cleaning and rinsing liquids on utensils. Such dishwashers also typically provide a limited selection of wash cycles. For example, a prior art dishwasher can provide a default wash cycle appropriate for most utensil loads and soil levels. Other cycles may include a “pots and pans” cycle for cleaning cooking utensils which may be heavily soiled. A “fragile” cycle can be used for china, crystal, glassware, and the like.
Prior art dishwashers also typically comprise a fixed spray arm assembly in the center of the dishwasher floor that sprays wash liquid uniformly throughout the wash chamber. This can result in wash liquid being sprayed in areas that have no utensils if the dishwasher contains less than a full load of utensils. Cleaning and resource usage is less than optimal due to the spraying of wash liquid in empty areas that could better be concentrated in areas occupied by utensils.
The availability of only a limited number of cycles can result in using wash cycles that may be inappropriate for some loads or for mixed loads. For example, a “pots and pans” cycle may be suitable for heavily-soiled cooking utensils, but may be overly hot and long for tableware, thereby contributing to excessive water, detergent, and energy consumption. Furthermore, selection of a wash cycle based upon the majority of the utensils in the dishwasher may result in incomplete cleaning of more heavily soiled utensils.
There is a need for a dishwashing system that can sense the load size and level of soiling of utensils within the dishwasher, and can adjust spray patterns, spray duration, and spray pressure based upon load size and soil levels at selected locations within the dishwasher.